Speed Enforced by 50 quintillion watt radar

A recent road trip caused me to read many signs regarding how local law enforcement were planning to deal with my potential speeding, and I am now quite afraid of the massive radar arrays that these folks appear to have installed. Specifically, I'm referring to the signs which say "Speed Enforced by Radar."

Enforcement is a strong word with a short definition "Compel obedience to." In states and counties where the speed is merely "checked" by radar, I assume that they are using the normal radar guns which bounce a beam off of my car and use the Doppler shift to register my rate of travel, allowing the officer to see that I am safely under the limit and turn his/her attention to some other potential law breaker and NOT SEARCH MY TRUNK FOR MARMOSETS, SINCE I DON'T HAVE ANY IN THERE.

No, the folks that actually plan to compel my obedience to the speed limit using radar are the scary ones. To do that, you would need to use something called "radiation pressure" which is a minuscule force, even when you are measuring the output of something who's radiation you can feel as warmth, like the sun. As an example, if we were at a place where the energy flux from the sun were about the boiling point of water (373.15 Kelvin) the radiation pressure would be about 2 lbs of force per square mile. Slowing down a speeding car by 5 or 10 miles per hour is going to take a heck of a lot more energy than 2 lbs / square mile.

I don't want to do the energy calculations for the requirements of a radar gun capable of enforcing speed limits, but I'm reasonably sure that it would require a captive black hole and a pretty serious array of antennas, likely electromagnetically focused (or a shaped gravity lens -- if you have a captive black hole already, why not?) In any event, the resulting EM beam would almost certainly vaporize the car, the occupant and any marmosets that you then couldn't prove were ever in my trunk. It would also vaporize anything in it's path until it cleared the horizon, and small chunks of the moon if it happened to be in the way.

Where are podunk counties in Northern California getting this kind of technology? Why aren't we seeing huge swaths of the countryside charred to pure carbon by their speed enforcement technology? I expect everyone is as frightened by the threat of radar enforced speed as I am, and don't dare speed in these places.

You may note that I've not addressed the signs saying "Speed Enforced by Aircraft" which are really scary too, but pretty obvious as to their method. It seems wasteful to destroy a whole airplane that way every time you want someone to slow down, but at least it doesn't burn holes in the moon.